Kings of Leon, one of the most popular rock acts in the world, have cancelled their entire U.S. tour, including a date slated for Saturday, Aug. 13 at the Comcast Theatre in Hartford.

The announcement came from the band after a particularly disastrous performance in Dallas.

King's of Leon's official statement on the tour cancellation was:

"We are so sorry to say Kings of Leon are canceling their entire US tour due to Caleb Followill suffering from vocal issues and exhaustion. The band is devastated, but in order to give their fans the shows they deserve, they need to take this break. Unfortunately, the US dates cannot be rescheduled due to the band's international tour schedule. Tickets will be refunded at point of purchase. Tickets purchased online or via phones will be automatically refunded. The band will resume touring in Canada at the Rogers Center in Vancouver, BC, on September 28th. That show was originally schedule for September 14th."

However, according to numerous media outlets including Rolling Stone, the announcement followed one turbulent performance in Dallas, which was shortened when lead singer Caleb Followill had to leave the stage to vomit.

While exhaustion was pointed to as the reason for the cancellation, according to Rolling Stone "comments from his brothers at the concert and on Twitter suggest that he may be dealing with a bigger issue. When apologizing on Twitter, bassist Jared Followill wrote "there are internal sicknesses & problems that have needed to be address" and "I know you guys aren't stupid. I can't lie. There are problems in our band bigger than not drinking enough Gatorade."

At the Dallas show on Friday Caleb left the stage and said "I'm gonna go backstage and I'm gonna vomit, I'm gonna drink a beer and I'm gonna come back out and play three more songs."

He never returned though. Instead Jared told the crowd, "Caleb's just a little unfit to play the rest of the show. We love you guys so much, but I know you guys (expletive) hate us. I'm so sorry. It's really not our fault, it's Caleb. He can't play the rest of the show. We will be back as soon as possible."